The F-16 fighter aircraft has a power supply that supplies power to missiles mounted on the airframe. The aircraft power supply is designed to produce 175 volts dc. Although the power supply is regulated, it is not overvoltage protected. The aircraft power supply is in an overvoltage condition when its output voltage exceeds 185 volts dc. If a missile was mounted to the aircraft during an overvoltage condition of the power supply, then the missile could be damaged to the point of either malfunction or failure. A recent survey by a defense contractor found that out of 70 aircraft power supplies, 12 power supplies exceeded the maximum voltage limit of the missiles; a 17% overvoltage rate. Therefore, what is needed is a test apparatus that can detect an overvoltage condition of the aircraft power supply.